This week’s episode features a discussion of the terms whale, dolphin, and porpoise. Did you know that a killer whale, otherwise known as an orca, is actually a dolphin? Orcas are in fact the largest dolphin species in the world today. So, why are they called whales and not killer dolphins? Well, that is a good question, and there is no easy answer. So instead of an easy answer, here is a complicated one.
Did you know that a killer whale, otherwise known as an orca, is actually a dolphin? Orcas are in fact the largest dolphin species in the world today. So, why are they called whales and not killer dolphins? Which, by the way, sounds downright terrifying? Well, that is a good question, and there is no easy answer. So instead of an easy answer, here is a complicated one: There are around 35 species of oceanic dolphin. All of these species can be correctly referred to as dolphins because they are in the scientific family known as delphinidae. Species in this family all have cone shaped teeth, a single blowhole on the top of the head, among other morphological traits that separate them from the other families. What makes this a little confusing is that the common name for many of these dolphin species has the word ‘whale’ in the name. The killer whale is a fine example. But there are more, including the melon-headed whale, the pygmy killer whale, the false killer whale, the long-finned pilot whale, and the short-finned pilot whale. To complicate the issue even further, all of the species I just listed are sometimes called blackfish, although they are of course not actually fish, and not really whales, but simply dolphins.
You think that is confusing? Try figuring out how the word porpoise fits in. In North America, many people refer to dolphins (the species in the family delphinidae) as porpoises. They may even call a bottlenose dolphin, the most famous dolphin of all, simply a porpoise. This term came about from fisherman who call most dolphin species a porpoise to differentiate between them and the dolphin fish, otherwise known as mahi-mahi. Now the problem is that science recognizes the porpoise as a different kind of animal altogether. There is a scientific family known as phocoenidae that contains 6 species of what are officially known in science as porpoises. So to be scientifically proper, a porpoise is an animal belonging to the phocoenidae family, and the term porpoise should only be used to describe one of those 6 species. Unless of course you are a fisherman and you want to call a melon-headed whale a porpoise, which you might do, even though it is actually a blackfish or officially a dolphin.
But let us return to the first question: what us a whale? Well according to official scientific terminology, there is no such thing as a whale at all. Science does not formally use the standalone word ‘whale’ to refer to any of the animals found in the scientific order cetacea; that is the order containing all animals commonly referred to as whales, dolphins and porpoises. The term whale is usually used in the common name of the largest of the animals in the order cetacea, including the blue whale, the sperm whale and the beluga whale. That is because the word whale in English was in use for many centuries before scientists came on the scene and tried classify all of the cetaceans, and it was probably applied rather indiscriminately to most large animals seen swimming in the oceans. Nowadays, a scientist might refer to animals like the blue whale (a species with baleen instead of teeth and grooves on their throats) as rorquals, or they might call the Sperm whale by the name Physeter. Because common names often vary from place to place and language to language, the only way to be sure of what animal you are talking about is to use its scientific name. In English, a Killer Whale therefore was probably originally referred to as a whale simply because it is large; it otherwise has very little in common with an animal like the Blue whale. As we now know, science recognizes the Killer Whale as a dolphin because it is in the delphinidae family.
But here is one more snag: there are 5 species of freshwater river dolphins that are NOT in the dolphin family, but in separate families altogether. These river dolphins are nonetheless correctly referred to as dolphins. As you can see, it is not easy to tell a dolphin from a whale. When in doubt, you can always just shout ‘hey, look – there’s a cetacean! ‘ Maybe that is cheating, but at least you will be correct! Wouldn’t it be easier if we all just spoke Latin?